Notes from the Field: Increases in Imported Malaria Cases - Three Southern U.S. Border Jurisdictions, 2023.

Malaria is a severe and potentially fatal mosquitoborne disease caused by infection with Plasmodium spp. parasites. Although malaria is no longer endemic in the United States, imported infections are reported annually; the primary risk group has been U.S. residents traveling to areas where malaria is endemic (1). In 2023, sporadic locally acquired mosquito-transmitted malaria cases were reported in several U.S. states (2,3). This report describes increases in imported malaria cases in 2023 compared with 2022 in three public health jurisdictions along the U.S. southern border.

Tick-Borne Relapsing Fever in the White Mountains, Arizona, USA, 2013-2018.

Tick-borne relapsing fever (TBRF) is a bacterial infection transmitted by tick bites that occurs in several different parts of the world, including the western United States. We describe 6 cases of TBRF acquired in the White Mountains of Arizona, USA, and diagnosed during 2013-2018. All but 1 case-patient had recurrent fever, and some had marked laboratory abnormalities, including leukopenia, thrombocytopenia, hyperbilirubinemia, and elevated aminotransaminases. One patient had uveitis. Diagnosis was delayed in 5 of the cases; all case-patients responded to therapy with doxycycline. Two patients had Jarisch-Herxheimer reactions. The White Mountains of Arizona have not been previously considered a region of high incidence for TBRF. These 6 cases likely represent a larger number of cases that might have been undiagnosed. Clinicians should be aware of TBRF in patients who reside, recreate, or travel to this area and especially for those who sleep overnight in cabins there.

Greening Up For Mosquitoes: A Comparison of Green Stormwater Infrastructure in a Semiarid Region.

Green stormwater infrastructure provides environmental, economic, and health benefits as a strategy for building resilience against climate change impacts. However, it may inadvertently increase vulnerability due to improper design and construction or lack of maintenance. We engaged city stakeholders and a diverse student group to investigate possible maladaptation. After rain events, student interns collected data at green stormwater infrastructure, identified in partnership with city stakeholders, for both water retention and mosquito larvae, if present. During the sampling period in 2018, 24 rain events occurred, with 28 sites visited 212 times including visits to basins (63%), curb cuts (34%), and a bioswale (2%). The largest basin consistently retained water (mean: 3.3 days, SD: 2.3 days) and was a positive site for Culex quinquefasciatus, a West Nile virus vector. We found that while basins can become mosquito breeding habitat, there was no evidence that curb cuts were collecting and retaining water long enough. As cities turn to green stormwater infrastructure to address climate change impacts of increasing drought, flooding, and extreme heat, these findings can help in the selection of appropriate infrastructure design typologies.

Recognizing the Role of Skunks in Human and Animal Rabies Exposures in the Southwest.

Rabies is arguably the most important viral zoonotic disease worldwide with an estimated 55,000 human deaths each year. Globally, dogs are the primary animals affected. In the United States, especially on the East Coast, raccoons and bats are the primary reservoir. However, in the southwestern United States, skunk and bat rabies play a large role. We describe the epidemiology and environmental risk factors associated with rabies in the US Southwest using exposure data for 2004-2012 from one Arizona county as a case study. Unlike other parts of the country, here bats and skunks are the most commonly collected positive animals (62% and 32%, respectively). Even though most of the positive animals were bats, human and domestic animal exposures were primarily a result of skunk interactions (58% and 50%, respectively). Consequently, the majority of exposures occur early in the year, January and February, when the majority of skunk pickups also occur. Using public health surveillance data, our study highlights the importance of recognizing the role of skunks in human and animal exposures in the southwestern United States. Consistent with a "One Health" approach, our data show how wildlife and domestic animal and human exposures are associated and informative to one another.